Indoleamine 2,3-dioxygenase (IDO) has been implicated in regulation of feto-maternal tolerance and protection against intracellular and extracellular pathogens. We have studied the expression of IDO in the human female reproductive tract and the placenta by immunohistochemistry. Endometrial glandular and surface epithelial cells showed increasing IDO expression during the course of the menstrual cycle. In term placenta, IDO was irregularly localized to the mesenchymal core and found in isolated areas of the syncytiotrophoblast. In first trimester pregnancy, IDO was not present in placental villi, but was present in glandular epithelium of the decidua, and there were distinctly positive cells scattered in the connective tissue, sometimes in conjunction with lymphoid aggregates. The endothelium of spiral arteries and of capillaries showed some, albeit no generalized, reactivity. IDO was also present in the epithelium of cervical glands and of Fallopian tubes. Specificity of antibody binding was confirmed by Western blot analysis. IDO mRNA was detected in first trimester decidua as determined by RT-PCR. IDO is secreted, as determined by analysis of cervical mucus by high pressure liquid chromatography for the presence of the tryptophan metabolite L-kynurenine, indicating IDO activity. Our results support the concept of IDO providing a mechanism of innate immunity protecting against ascending infections in the female reproductive tract.

Signal transduction via the endothelial receptor for advanced glycation end products (RAGE) plays a key role in vascular inflammation. Recent observations have shown that the myeloperoxidase-H2O2-chloride system of activated phagocytes is highly up-regulated under inflammatory conditions where hypochlorous acid (HOCl) is formed as the major oxidant. Albumin, an in vivo carrier for myeloperoxidase is highly vulnerable to oxidation and a major representative of circulating advanced oxidized proteins during inflammatory diseases. Immunohistochemical studies performed in the present study revealed marked colocalization of HOCl-modified epitopes with RAGE and albumin in sections of human atheroma, mainly at the endothelial lining. We show that albumin modified with physiologically relevant concentrations of HOCl, added as reagent or generated by the myeloperoxidase-H2O2-chloride system, is a high affinity ligand for RAGE. Albumin, modified by HOCl in the absence of free amino acids/carbohydrates/lipids to exclude formation of AGE-like structures, induced a rapid, RAGE-dependent activation of extracellular signal-regulated kinase 1/2 and up-regulation of the proinflammatory mediator monocyte chemoattractant protein-1. Cellular activation could be blocked either by a specific polyclonal anti-RAGE IgG and/or a specific mitogen-activated protein-kinase kinase inhibitor. The present study demonstrates that HOCl-modified albumin acts as a ligand for RAGE and promotes RAGE-mediated inflammatory complications.

Background and purpose: Endothelins (ETs) and their G protein-coupled receptors exert key physiological functions during normal and aberrant placental development. Trophoblast cells mediate the contact between the embryo and the mother, by establishing a transient organ, the placenta. Choriocarcinoma cells display many of the biochemical and morphological characteristics of in utero invasive trophoblast cells and may therefore be used as a suitable model to study epithelial tumour progression of foetal-derived cells. Experimental approach: The present study aimed at investigating ET receptor-mediated activation of the mitogen-activated protein kinase (MAPK) pathway in human choriocarcinoma. Key results: Both JAR and Jeg-3 choriocarcinoma cell lines expressed ET receptor subtype B (ET B ) but not ET A receptor transcripts. ET B receptor engagement by ET-1 and ET-3 resulted in a similar time-and concentration-dependent phosphorylation of p42/44 MAPK, also known as extracellular regulated kinase 1/2. Using specific pharmacological antagonists/inhibitors, we showed that ET-1/-3-mediated signal transduction by the ET B receptor is transmitted via G i -and G q -dependent pathways through activation of the Src (G i ) and protein kinase C (G q ) axis that converge at Ras/Raf, leading to downstream activation of p42/44. On a functional level, ET B engagement and subsequent phosphorylation of p42/44 resulted in enhanced transcription of the immediate early response genes c-fos and c-jun, a process commonly assumed to be mediated by the ET A receptor, and increased cell growth and relative cell area. Conclusions and implications: As human choriocarcinoma cells secrete ETs, pharmacological antagonism of ETs and/or ET B receptor-mediated signal transduction could represent a likely target therapy for choriocarcinoma.

Highlights► OxLDL promotes induction of pATM and p21 in fibroblasts/endothelial cells. ► OxLDL activates ATM-kinase by a doubled-stranded DNA break-independent mechanism. ► ATM-deficient fibroblasts exhibit low cell viability but increased oxidative stress towards oxLDL. ► ATM expression exerts protective effects against ox-LDL-induced cellular toxicity.

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